01 - Preheat the oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together the almond flour, oat flour, baking soda, and salt until evenly distributed.
03 - In a large bowl, beat the softened butter with light brown sugar and granulated sugar using an electric mixer until light and fluffy, about 2–3 minutes.
04 - Add the egg and vanilla extract to the butter mixture, beating until well combined and smooth.
05 - Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed until a soft, cohesive dough forms.
06 - Gently fold the chopped pistachios and dark chocolate into the dough until evenly distributed throughout.
07 - Scoop tablespoon-sized portions of dough onto the prepared baking sheets, spacing them about 2 inches apart. Flatten each mound slightly with your fingers or the back of a spoon.
08 - Bake for 10–12 minutes, rotating the sheets halfway through, until the edges are golden and the centers are just set.
09 - Let the cookies rest on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.